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Harvard Forest Research Project 2022

  • Title: Soil bacterial common garden experiment
  • Principal investigator: Kristen DeAngelis (kristen@post.harvard.edu)
  • Institution: University of Massachusetts Amherst
  • Primary contact: Kristen DeAngelis (kristen@post.harvard.edu)
  • Team members: Mallory Choudoir; Achala Narayanan
  • Abstract:

    Three decades of soil warming in the temperate forest soils of Harvard Forest have resulted in massive loss of soil carbon stocks, and a decline in the quality of carbon remaining available to soil microbes. Along with this loss of soil organic matter, there has been a marked reduction in the soil microbial biomass. However, the biomass lost is seasonal and due to decreased fungal abundance, with bacterial biomass remaining stable. Against this background, bacterial communities have changed little, and isolate studies have demonstrated that bacteria from warmed soils have an enhanced ability to degrade cellulose and hemicellulose, but not chitin. This suggests that further adaptations related to fitness could be possible.

    This experiment is designed to test the hypothesis that thirty years of warming has increased the fitness of bacteria from heated soils compared to those from control soils.

    The objective is to measure how site of origin (heated versus control) affects the ability for bacterial isolates to grow in soils. To do this, we will grow bacteria from heated and control soils in microbial cages incubated for one growing season in heated and control soils. Fitness will be measured based on change in cell counts based on direct observation using microscopy, colony forming units, and quantitative PCR.